Smartcom Multizone control panels can control up to 16 heaters in a network. Please see the C30 SmartCom3 Control Panel Installation and User Manual (https://www.reznor.co.uk/wp-content/uploads/2023/12/2a.-704020-SC3ML-Installation-and-Operating-Manual-v3a-Ben-EN-0416-A4F-GBSCOM1200416-1.pdf) for more information.
How many heaters can be controlled by a Smartcom control panel network?
Information on Reznor's range of control panels